Pool: THE VEGETATION OF THE SANDHILLS OF NEBRASKA 221 



the Uplands become of less extent. This condition is most notice- 

 able as one goes north and east where occur extensive lake and 

 marsh regions as in eastern Cherry County and southwestern Brown 

 County. The increasing proportion of lowlands as the eastern and 

 northeastern limits of the sandhills is approached is very pronounced 

 until, as one finds in southern Holt County and in Antelope County, 

 the typical expression of the bunch-grass association is restricted to 

 the widely scattered ranges of hills that serve as narrow boundaries 

 of wide and flat natural meadows. The most widely isolated spurs 

 of sandhills retain much of their typical sandhill characters for a 

 surprisingly long time. 



Toward the southeastern and northern portions of the sandhill 

 region the sandy soil appears to give way more abruptly to the loess 

 region and consequently the distribution of the bunch-grass associa- 

 tion is here terminated by a more clear-cut boundary line. West- 

 ward the transition from sandhills to the firm soil of the high plains 

 with its short-grass cover is as a rule quickly made and there are 

 few scattered ranges of sandhills on this border that reveal the 

 presence of the bunch-grass association. 



The plants that share in the botanical composition of this asso- 

 ciation as it occurs in the Nebraska sandhills are shown in the fol- 

 lowing lists of species which are classified into three groups based 

 upon their relative abundance. 



Composition of the Bunch-Grass Association 

 dominant species 

 Andropogon hallii Andropogon scoparius 



PRINCIPAL SPECIES 



Calamovilfa longifolia Primus besscyi^ 



Carex stenophylla Psoralea lanceolata^ 



Ceanothus ovatus pubescens^ Rosa arkansana^ 



Helianthus subrhomboideus^ Stipa comatd^ 



Meriolix serridata Yucca glauca^ 

 Muhlenbergia pungens^ 



SECONDARY SPECIES 



Acerates angustifolia Allionia hirsuta 



Acerates lanuginosa Allionia linearis 



Acerates virididora Amorpha canescens^ 



Acerates viridiflora ivesii Androsace occidentalis 



Acerates viridiflora linearis Anemone caroliniana 



